Flash detection for firefox_svg_plugin

Good test case

Author: wchen-r7

modules/exploits/multi/browser/firefox_svg_plugin.rb

@@ -75,7 +75,8 @@ def initialize(info = {})
       'BrowserRequirements' => {
         :source  => 'script',
         :ua_name => HttpClients::FF,
-        :ua_ver  => /17\..*/
+        :ua_ver  => /17\..*/,
+        :flash   => /[\d.]+/
       }
     ))